Motorcycle tire and wheel assemblies are generally constructed of steel or alloy rim with a latticework of spokes that attach the rim to the hub. They may also be constructed of a cast alloy hub/rim assembly with open cutaway spaces between the rim and hub. Either type of wheel assembly would applicable to this invention.
Acceleration and deceleration of the motorcycle or other vehicle tends to cause the tire to rotate on the rim. Rotation of the tire on the rim is not desirable because it can cause the wheel assembly to become unbalanced. In the case of tubed tires (an inner air-filled bladder within the tire carcass) any rotation of the tire can cause the tube's valve stem to tear away from the main tube bladder, leading to a sudden and catastrophic loss of air pressure. In the case of tubeless tires (no inner air bladder) rotation of the tire on the rim can cause a gradual loss of air pressure, with an eventual loss of bead-to-rim contact, and potential catastrophic loss of air pressure.
When a rubber motorcycle tire is mounted to the metal hub/spoke/rim assembly, it is held in place with a combination of air pressure, tension of the rubber tire itself which exerts an outward (sideways) force, and friction between the rubber tire sidewall and the metal rim. Often the motorcycle manufacturer or tire installer uses special lubricant/adhesive solution that literally “glues” the rubber tire in place on the rim. Even without this solution the rubber tends to “fuse” itself to the rim over time and tire removal can become very difficult.
Additionally, motorcycle tires are often mounted on what's called “safety rims” or “locking rims”. The design of these rims is such that the tire's sidewall and annular bead is retained in such as manner as to prevent movement of the tire within the rim, when subjected to the high stresses involved in turning or cornering maneuvers. The design of these rims makes tire removal nearly impossible without specialty tools.
When it's time to change a motorcycle tire due to road wear or to make a repair of the tube or otherwise perform any repairs on the tire, it is necessary to “break the bead”. This is a commonly used term that refers to the process of breaking the adhesive and/or mechanical seal between the rubber sidewall of the tire, and the rim itself. Due to the design of modern tires, which are physically wider than the rim itself, and because of the widespread use of lubricant/adhesives holding the tire in place on the rim, this process can be extremely difficult (if not impossible) unless you have proper tools.
The process of changing or repairing a tire on an automobile is considered relatively easy because nearly every car has a spare tire, and when a flat tire has been removed from the automobile almost every service station has the necessary professional equipment and training to fix or replace an automotive tire.
However, the process of changing or repairing a motorcycle tire is a different story because most motorcycles can't carry spare tires. Motorcycle shops are few and far between so whenever a motorcycle has a flat tire the rider is often forced to make roadside repairs using whatever tools he/she might carry with them. The alternative is to call for a towing service and have the motorcycle hauled to the dealership for repair.
For those who attempt to repair motorcycle tires or for those who change their own tires when the tires become worn, the first step in the process is to deflate the tire (in the case of a flat tire this has already occurred). The second step is to remove the tire and wheel assembly from the motorcycle. The third step is to “break the bead” or otherwise break the seal between the rubber tire and the metal rim. Finally the tire can be removed from the rim and repaired or replaced.
Currently there are very few (if any) tools compact enough, lightweight enough, or otherwise suitable for this process. Motorcyclists have responded to this lack of suitable tools by concocting a variety of expedient devices, including C-clamps (or modifications thereof), or wedges driven between the tire and rim using a hammer or mallet, or some sort of pure brute force method, including jumping up and down on the side of the rubber tire (while trying to avoid jumping on the rim itself).
One popular technique is to use a second motorcycle's side stand as a tool to wedge between the tire and rim, while rocking the second motorcycle so that its' weight presses down on the side stand and hopefully breaks the bead. This method may work but often results in damage to the side stand, as well as damaging the rim. Whatever method is used the process is difficult and sometimes dangerous. It may be necessary to exert a force of more than 500 pounds to break the seal between the metal rim and tire. As rubber tires get older this bead breaking process becomes even more difficult because the rubber compounds become stiffer and less pliable. Also, as ambient temperatures drop the process becomes increasingly difficult.
This embodiment utilizes a simple fulcrum and lever device that compounds the user's downward weight, thereby forcing a wedge-shaped plunger member into the space between the rim and wheel. With sufficient extension of the lever the force exerted can easily exceed 1000 pounds, which has proven to be more than enough force to unseat a motorcycle tire bead from a rim.
This embodiment can be used in any location having a flat, relatively hard work surface. The tire assembly must first be removed from the motorcycle and placed in a horizontal position; in other words, the wheel assembly must be resting flat on the ground.
This embodiment can also be used in any location having a flat, soft surface such as sandy soil or bare earth. This can be accomplished by the addition of wooden or metal strips fixed at perpendicular angles to the device, placed so as to widen the “footprint” of the device and prevent it from sinking in the soil when downward pressure is applied to the embodiment or to the tire assembly.
Although the working model of this embodiment is sized as shown in the drawings, production models could be constructed to any scale, depending on the need of the user or the size of the wheel assembly.
Once the motorcycle operator has successfully “broken the bead” on the tire, they must then make repairs to the tire. This requires removing the pneumatic tire from the metal rim. This is done with a set of two or three metal “tire irons”, which are essentially flattened pry bars.
Tire irons can be of varying size and shape, but for practical purposes and ease of carry on a motorcycle they should be as compact and lightweight as possible. The typical tire iron used for this embodiment is about 0.25″ thick, 0.75″ wide, and about 8″ to 10″ long. Each end of the tire iron is shaped and designed to make tire removal process as easy as possible, and smooth to prevent damage to the tire carcass or the inner tube.
To remove a tire from a metal rim the user places a tire iron between the metal rim and the pneumatic tire and using the leverage provided by the tire iron forces the circumferential inner bead of the tire over the edge of the rim. The user repeats this process around the tire assembly until one side of the tire comes off the rim. The user then repeats the process on the remaining tire sidewall until the tire has been completely separated from the rim. At that point the tire can be repaired, replaced, or the inner tube can be repaired or replaced.
To install a tire on a metal rim the user places a tire iron between the metal rim and pneumatic tire and forces the tire bead over the edge of the rim, then repeats the process around the tire until the tire is on the rim. The user repeats the process on the other sidewall of the tire until the tire is fully onto the rim, at which time the tire is filled with air. In the case of a tubed tire the tube is inserted into the tire before the second sidewall is forced onto the rim.